研究目的
Investigating the effects of hydrostatic pressure on the surface plasmon resonance of gold nanospheres and nanorods to deduce the mechanical stiffness of the crystals.
研究成果
The study concludes that the bulk modulus of gold nanoparticles is about 15% higher than that of bulk gold, with a value of 190 GPa. Pressure-induced solidification of the solvent leads to aggregation and deformation of the nanoparticles, causing significant broadening and anomalous shifts in the surface plasmon band.
研究不足
The study is limited by the hydrostatic range of the pressure-transmitting media and the potential for non-hydrostatic effects at higher pressures. The analysis assumes no change in particle shape under hydrostatic load, which may not hold if plastic deformations occur.
1:Experimental Design and Method Selection:
The study used optical absorption spectroscopy to measure the surface plasmon resonances of gold nanospheres and nanorods under hydrostatic pressure. The Mie-Gans model was employed to interpret the spectral shifts.
2:Sample Selection and Data Sources:
Gold nanorods (GNR) and nanospheres (GNS) were synthesized and stabilized in methanol-ethanol mixtures or paraffin. TEM images were used to characterize the nanoparticles.
3:List of Experimental Equipment and Materials:
Diamond anvil cells (DACs) for high-pressure experiments, a Cary 6000i spectrophotometer for optical absorption spectra, and a Tecnai FEI20 TEM instrument for electron microscopy.
4:Experimental Procedures and Operational Workflow:
High-pressure optical spectroscopy was performed using a home-built fiber-optic based microscope. The pressure was measured using ruby microspheres as pressure probes.
5:Data Analysis Methods:
The spectral shifts were analyzed using the Mie-Gans theory to account for the SPR behavior under hydrostatic pressure. The bulk modulus was extracted by fitting the experimental data to an Equation of State.
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